During the operation of an internal exhaust gas system, exhaust gases are generated which must be subsequently treated by means of an exhaust gas system in order to make the operation of the internal combustion engine compliant with environmental regulations, such as for examples the regulations for exhaust gas limits. In this case, the success of the post-treatment depends on the functional operability of each component of the exhaust gas system, such as for example a catalytic converter or a lambda sensor. As a result of the tightening of exhaust gas limits everywhere in the world, the requirements on the diagnosis and on the operation of gas exhaust gas system are steadily rising.
Since in order to test an exhaust gas system, both operating conditions with a rich mixture as well as operating conditions with a lean mixture of respective internal combustion engines are required, a diagnosis of an exhaust gas system of the internal combustion engine which is independent of the operating point regularly leads to additional consumption and thus also to worsening emission values of the internal combustion engine.
In the German document DE 10 2008 027 575 A1 is disclosed a diagnostic method for a catalytically effective gas exhaust purification element of an internal combustion engine.
A method for testing a particle filter for exhaust gases from a gasoline engine is disclosed in the German document DE 10 2011 106 933 A1.
The German document DE 10 2009 000 410 A1 discloses a method and a device for diagnosing an exhaust post-treatment device by means of voltage sequences of a number of lambda sensors.
From U.S. Pat. No. 6,600,998 B1 is known a method according to which 02 saturation is detected and when a threshold value is reached, the control over the engine is correspondingly adjusted. At the same time, the mixture is enriched during a predetermined period of time.
In the publication “Wissenschaft Populär: Vier Wege zum sauberen Benzinmotor” (Popular Science: Four Roads to a Clean Gasoline Engine), issued by BASF in December of 2010, is disclosed a catalytic converter system which removes the gaseous pollutants and soot particles from the exhaust gas. In this case, the three-way catalytic converter was expanded to a four-way catalytic converter so that solids can be removed from the exhaust gas, wherein only a small counter-pressure is built up.
Further, an OBD diagnostic system method is known from the US law described in the California Code of Regulations, § 1971.1, On-Board Diagnostic System Requirements—2010 and Subsequent Model Year Heavy-Duty Engine.
A method for dynamically diagnosing an exhaust sensor in an exhaust gas channel is known from the document DE 10 2006 041 477 A1.
Finally, from the document US 2003/0154709 A1 is known a diagnostic device for an exhaust gas sensor, which is arranged in a diagnostic device for diagnosing a sensor abnormality and which evaluates the sensor based on the exhaust gases after the combustion engine has been turned off.